Indicating device



0a.1,1935. E ALECH, 1 2,016,149

INDICATING DEVICE Filed July 20, 1933 25.123/ za b 14W, ai)

E His ATLoPneg.

Patented Oct. l, 1935 uNlraowsTArEs PATENroFl-lca 2,016,149 i `rNn'lcyrmc;` 1pavlor. e 'Edward A. Leach, Schenectady, N. Y., assigner to GeneralfElectric Company, a corporation of New `York Animation July 2p, 193e, serial No. 681,325

` 5 Claims.y (Cl. 'I4-305) My invention relates'toindicating devices and more particularly to improved means ofthat type which has a vernier indicating scale. v

In providing indicators for adjustable means it frequently has been desirable to provide a Vernier indicator moving at acertain ratio` with respect to the main indicator. Such arrangements usually involve gear systems which inherently introduce a certain'amfount of backlash between the indicators. Devices attempting to eliminate the effect of backlash have generally utilized frictional means which increased the torque necessary to make adjustments and, furthermore, after 'considerable use require adjustments and Vgenerally were unsatisfactory. ,V

In radio apparatus, particularly radio transmitters, it is necessary to have an indicator which will provide fine, accurate indications of the adjustment of the tuning device. It is further desirable that the adjusting knob produce a slow adjustment -so that small increments of adjustment of the tuning device may be obtained. The

friction between the tuning device and the adjust ing knob should be relatively'small so that these small increments of adjustment may be made easily andreadily.

`It is an object of my invention to provide a vernier indicator with improved means for preventing backlash without appreciably` increasing the friction of the device.

It is a further object of my1 invention to provide an indicating device; suitableV foradjusting radio apparatus, with an epicyclic gear system wherein backlash is eliminated. A

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization `and method of operation together with further objects and advantages thereof may bev understood bestby reference to the following description taken in connection withjthe accompanying drawing in which Figs.,l, 2, 3 show respectively` front, rear and cross-sectional views of a device wherein my invention has been embodied; Figs. 4, 5, 6 show details of the device, and Figs. 7 and 8 indicate diagrammatically certain modifications thereof. v

Referring to Fig. 1 of the drawing, I have illustrated therein the panel I of a radio apparatus which supports the escutcheon 2 of the device embodying my invention. "The escutcheon is `provided with two openingsthrough which the indicating scale 3 and the Vernier scale 4 are visible. On the front of the escutcheon there are provided the knob 5 for actuating the mechanism and the knob 6 for locking the mechanism after adjustment has been made.

Reference may now be had to Fig. 2 which shows the back view of the device, and to Fig. 3

which is a cross-section viewed in the direction of the arrows III of Fig. 2. `The actuating'knob 5 is secured to a shaft 'I which extends through the escutcheon 2 to a journal'membera. 'I'he Vernier scale 4 is fastened to the knob 5 by means 5 of screws 9. The shaft 1 has secured thereto a.` driving gear IU which engages the intermediate gears II, I2 and I3. These intermediate gears in -turn engage the ring gear I4 which is secured ina stationary position by the cap screws I5 10 which Yextend through the panel Il from the escutcheon 2. 'Ihe intermediate gears Il and I2 are securely journaled in front and rear plates I6 and Il which are spaced by a spacing member I 9 and held in position by means ofbolts 20. 15

The knob 6 is attached to a shaft 2l, one extremity of which is threaded. A nut member'22 is mounted on the threaded portion of the shaft 2| and is prevented from rotating by a guide pin 23. The `nut member 22 is preventedfrom com- 20 ing voff on the threaded portion of the shaft by means of a suitable cotter key 24. When the knob 5 shown in Fig. 3 is rotated so as tovcause the nut member 22 to move to the right, this member will engage the rear plate Il, thereby 25 holding it in position. l e

Fig. 4 is a cross-section of the bearing such as used in gears I l and I2 when viewed in the direc- Vtion of the arrows IV shown in Fig. 2. The bearing member Iltis journaled Yin the front and rear 30 plates I6 and I1 and the gear I2 is supported therebetweenlby the bearing member I8.

'Referencemay now be had to Fig. 2 and Fig. 5,

" the latter of which is' a cross-section of that porjournaled in the arm 29 and the block 30. A 45 spring 3l is` arranged between the block 30 and a spring retaining member 32 which is journaled on one extremity ofthe adjusting screw 26. The arm 29 is secured at `one extremity by the bolt 20. Thearm 29kislmaintained within operating limits 50 by a cap` screw 33 whichpasses through a large opening in the arm.. This can be seen best by referring to Fig. 6 which is a cross-section of the bolt viewedin the direction` of the arrows VI shown in Fig. 2. The cap `screw 33 is threaded 55 into the member Il and is provided with a spacer 34 so that the washer on the cap screw 33 will not bind against the arm 29.

In the epicyclic gear system shown, and described above, the gear I0 is the driving gear, 60

v.the spring member 3I.

so that they rotate` about their respective axes,v

and also progressyabont the axis or the driving gear I0. The progression of the intermediate gears 'about the axis of a driving gear I0 providesl The Journal motion of the plates I6 and I1. member 8 of the shaft I is attached to the rear plate I1. This journal member 8 may be coupled to the tuning condenser of a radio apparatus or any other device which is to be adjusted. The actuati-on of the knob 5 vwill cause the Vernier scale 4 to move with it, and the main scale 3 which is attached to the front plate I6 will, move more slowly. Fast actuation of the knob 5 will provide slow motion of the device to be adjusted and a vernier indication of the adjustment will be obtained.

Due Ato the fact that gears are used in this arrangement, it -is evident that the clearance necessary Ior the proper operation of the gears would introduce al backlash between the two scales were no means provided for eliminating such backlash. The means I3 and 26 to 33 cooperate to provide an arrangement for eliminating backlash. The spring member 3i exerts a `force against the driven arm of the system or in other words, the back plate II. 'A force is also exerted by the spring against the bearing 28 of the intermediate gear I3. This force between the driven arm of the system and the bearing of the gear I3 tends to cause the gear I3 to progress clockwise and to drive the driven arm counterclockwise when viewed as in Fig. 2. Due to this tendency of gear I3 to move in a direction opposite to the movement of the gears I I and I2, the clearance provided for proper meshing `of the gear teeth is taken up by the action of the force exerted by the spring member 3i. It is to be understood, however, that the spring member 3| producessuiiicient tension so that it is always `greater than the moment of force', introduced` into thesystem by the rotation ofthe knob! to produce adjustment of the device connectedto journal member Ii. Under this condition then there is no backlash and the friction introduced by the pressure ofthe gears against` the ring gear I4 and the driving gear I0 does notoomprise an appreciable amount.

In-Fig. 7 the various gears are indicated by circles,` the crosshatching on the outer circle or Aring gear indicating that this member is fixed. The dotted line indicates that the gears II and I2 comprise the driven arm of the system. The arrowed lineSI indicates the force introduced by Inasmuch as the force introduced by the spring 3| takes up the clearance provided for theproper engagement of the teeth on the gears, vit is evident thatthis arrangement eliminates the backlash between the driving gear and driven member.

Fig. 8 shows an arrangement similar to Fig. 7 in which the backlash has been eliminated between the driving gear and the driven member.

In this iigure, however, it will be noted that the gear I is shown as being a xed gear. The ring gear in this arrangement may be considered to be the driving gear of the epicyclic gear system.

The ring gear may be driven by a suitable gear engaging the periphery of the ring gear. rangement disclosed in this ligure shows that the specific embodiments set forth in Figs. 1 to 0 are susceptible of modification so that the vernielnot wish to be limited thereto, since it is apparent that the principles herein disclosed are susceptible of numerous other applications, and modifications may be made in the mechanical 4arrangements and in the instrumentalities employed without departing Afrom the spirit and scope of my invention as set forth in the appended claims. p

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an indicating device, an epicyclic gear system comprising `a driving gear, a ilxed gear, a plurality of gears intermediate,` said fixed and driving gear, certain of said intermediate gears constituting the driven arm of said system, and means connected between said arms and the other of said intermediate gears for reducing backlash between said driven arm and said driving gear. 2.v In anY indicating device,y an epicyclic gear l system comprising a driving gear, a xed gear, a

,plurality of gears intermediate said xed and driving gear, certain of said intermediate gears constituting the driven arm of said system, and

Ameans connected between said arm and the other of said intermediate gears for reducing backlash between said driven arm and said driving gear,

said means exerting a pressure between said arm and the axis kof said intermediategear.

3. 'I'he combination, in an epicyclic lgearing system, of agear rotatable about its own axis, 45.

a plurality of epicyclic gears in engagement therewith, and meansto overcome backlash in said system, said means comprising means resiliently to apply a force tending to rotate one of c said epicyclic gears with respect to the other 50.

about said first mentioned gearf said force be- Aing suiiicient to eliminate said backlash.

4. In combination', a fixed ring gear, a central gear, a plurality of gears intermediate said ring and central gears, and means to apply a force between saidintermediate gears tending to ro-` tate one of said intermediate gears with respect to the other about said central gear, said force being suilicient to overcome backlash between said gears. n

5. The combination, of an epicyclic gear lystem including a driving gear, a iixed gear, a plurality of intermediate gears each engaging said fixed and driving gears, certain ofsald intermediate gears constituting the driven arm ci' g5 said system, and means connected between said driven arm and another of said intermediate gears for preventing` backlash between laid driving gear and said .driver arm. 

